Thanks so much for the feedback. I actually tried to extend the Key
CONTAINS concept to other fields but ran into a big wall right away.
It would be great to get your 2 cents. Here is the root of my
problem:
I have a student object, it has a number of qualifying attributes, for
example:
int gpa: 1 = 0 to 2.0, 2 = 2.0 to 3.0, 3 = 3.0 to 4.0
int ageGroup: 1 = 0 to 17, 2 = 18 to 30, 3 = 30 to 65, 4 = 65+
ArrayList schoolPreference: [0] = 'MIT', [1] = 'Stanford', [2] =
'Harvard', [3] = 'Yale'
Now, I need to create a query to find out all the students where (gpa
= 2 or gpa = 3) AND (age group = 3 or age group = 4) AND
(schoolPreference contains MIT or Yale, or both)
As far as I know, GAE doesn't support OR operator in a query, so the
only way I can get the query above to work is to have multiple sub-
queries and do a manual join on all the datastore resultsets to
artificially create a union. If so, big problem arises:
Since I have so many OR sub-conditions, if every OR translates into a
separate sub-query, literally speaking, I need to do a full
permutation of all the conditions (full product of all the OR and AND
conditions) in all my sub-queries to achieve my goal, which doesn't
make any sense if I keep adding more value types (such as more schools
being selected in the student preference criteria) into my attributes,
not to mention adding more attributes to my student object. Is there
any way to accomplish this query in GAE? Your help is greatly
appreciated because this can be the deal breaker of whether my whole
project can migrate to GAE or not. Thanks a lot in advance.
On Oct 23, 1:51 am, Yasuo Higa <higaya...@gmail.com> wrote:
> Hi Andy,
>
> >> query.setFilter("key == :keyList");
> >> List<Master> list = (List<Master>) query.execute(keyList);
>
> > I'd like to know if that works with GAE/J, because it is illegal JDOQL
> > syntax and would be a bug. JDOQL is supposed to follow Java syntax,
> > and you simply cannot do
> > Key == List<Key>
> > and get success in Java.
>
> You are right, but unfortunately the above query works on GAE/J.
>
> I should have recommended the following query:
>
> List<Key> keys = ...;
> List<Object> ids = new ArrayList<Object>();
> for (Key key : keys) {
> ids.add(pm.newObjectIdInstance(Master.class, key));}
>
> List<Master> list = (List<Master>) pm.getObjectsById(ids);
>
> Thanks,
>
> Yasuo Higa
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